Because it would be pretty weird if they all just quacked…like a donkey quacking, an elephant quacking, a giraffe quacking. wait…what sound DO giraffes make???

Animals communicate differently – their voice boxes are different but some animals can obviously mimic human noises (like parrots) so they are not always that mechanistically different. so they can make different sounds because of their voiceboxes…but why don’t they all make the same noises? not an exceptionally easy one to answer. I think there are social issues involved…maybe all the giraffes that quacked died out because the other giraffes were like “what the flip is he saying? freak, he sounds like a duck!! don’t go anywhere near him!”

Hi melissa! Animals have different vocal structures so that is how they make different sounds. The why has to do with evolutionary history. Each animal has lived in a unique habitat and adapted to it. These different places can put different selective pressures on the organism causing differences like vocalizations to appear. I also think that animals adapt different sounds so they can identify their own kind! For example, Amy mentioned giraffes that might quack. That would be crazy! For one giraffes might start identifying ducks as giraffes which would be all wrong. Also quacking might make them susceptible to predators like lions that ducks never have to face. So there are a lot of factors, but the important thing to note is that uniqueness is a good thing in the wild!

Hi Melissa. The question has been pretty well answered by the others. Here’s a tip though – look up Lyrebirds on Youtube. They are an Australian bird, and the world’s best mimic. The male lyrebirds collect different sounds to impress their girlfriends – including not only animals and humans but construction equipment.